Roll changers

ABSTRACT

A roll changer for rapidly changing the work rolls of a rolling mill particularly designed for incorporation into existing mills. The roll changer includes a cartridge adapted to support the work rolls during a roll changing operation and provided with rotatable wheels which are turned by a rotatable rail section on a side shifting platform so that the work roll carrying cartridge can be moved into and out of the mill along a first pair of rails and transversely on a second set of rails during a side shifting operation.

United States Patent Eibe [54] ROLL CHANGERS [72] inventor: Werner W. Eibe, Pittsburgh, Pa.

[73] Assignee: Blaw-Knox Foundry 8: Mill Machinery, Inc., Pittsburgh, Pa.

22 Filed: July 1, 1971 211 App]. No.: 158,930

[52] US. Cl. ..72/239 [51] Int. Cl. ..B2lb 31/08 [58] Field of Search ..72/239, 238

[56] References Cited UNITED STATES PATENTS 3,451,244 6/1969 Stover et al ..72/239 1.5] 3,698,226 51 Oct. 17, 1972 Primary Examiner-Milton S. Mehr Attorney-Smith, Harding, Earley & Follmer ABSTRACT A roll changer for rapidly changing the work rolls of a rolling mill particularly designed for incorporation into existing mills. The roll changer includes a cartridge adapted to support the work rolls during a roll changing operation and provided with rotatable wheels which are turned by a rotatable rail section on a side shifting platform so that the work roll carrying cartridge can be moved into and out of the mill along a first pair of rails and transversely on a second set of rails during a side shifting operation.

30 Claims, 18 Drawing Figures Bohnenkamp ..72/238 PATENTEDUCT 17 m2 SHEET 1 [IF 8 OE mm mom PATENTEDum 17 I972 SHEET 5 OF 8 FIG. II.

INVENTOR WERNER W. EIBE ATTORNEYS PATENTEDnm 17 I972 SHEET 7 BF 8 Q QI PATENTEDnm 17 I972 sum 8 0F 8 mvEmoR WERNER w. EIBE ATTORNEYS ROLL CHANGERS BACKGROUND OF THE INVENTION This invention relates generally to roll changers and particularly to apparatus for automatically changing the work rolls of a rolling mill such as a hot strip mill.

The problem of changing work rolls in steel rolling mills has been a matter of increasing importance in the efficient operation of modern rolling mills. With modern high speed rolling mills it is frequently necessary to change work rolls serveral times each shift because of the changing nature of orders available, because of steel analysis, or for any of a variety of reasons all recognized in the trade. In the past, rolls were changed by overhead cranes using counterweighted porter bars or C-type hooks or some other device for individually handling a roll into and out of a rolling mill housing. Such methods as were heretofore available were excessively wasteful of time and manpower. With such methods more time could be spent in changing rolls than in actual rolling using modern high speed mills. Attempts have been made to eliminate this lost time and expense such as, for example the roll changers shown in US. Pat. No. 3,540,253 and in application Ser. No. 93,727 filed Nov. 30, I970.

The prior art proposals, however, are not particularly well adapted for incorporation in an existing rolling mill. This is primarily because the prior designs would require extensive reconstruction of the existing mill and the discarding of expensive equipment associated with the existing mill.

SUMMARY OF THE INVENTION The present invention provides a roll changer design for the rapid automatic work roll changing of a rolling mill, which design can be incorporated in an existing hot strip mill with a minimum of expense. The design in accordance with the invention can be erected without interruption of the production of the mill by keeping the work at the mill stand proper to a minimum so that it can be performed during the normal downturns of the mill Moreover, the design does not require new work roll chocks and under normal circumstances does not require mechanical, spring-loaded stools or a false floor. Furthermore, the design does not require any substantial foundation removal and renewal.

Briefly stated, the design in accordance with the invention comprises a cartridge means which is adapted to support the work rolls of the mill and carry them into and out of the mill, and a side shifting means involving a single station providing a very compact arrangement. The cartridge means has turnable wheels which are adapted to ride on tracks on the side shifting means guiding the cartridge for movement toward and away from the mill and transversely in a direction along the mill.

Various alternate forms of construction will be described in connection with the adaptability of the design to various types of existing mills.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a rolling mill stand including the roll changing design in accordance with the invention;

FIG. 2 is a side elevation of the mill shown in FIG. 1 with various parts shown in alternate operative positions and various parts eliminated for the sake of clari- FIG. 3 is an end elevation view showing the side shifting means;

FIG. 4 is a top plan view of the side shifting means employed in the mill shown in FIG. 1;

FIG. 5 is a sectional view taken generally on line 5- 5 of FIG. 4;

FIG. 6 is an enlarged view of a detail;

FIG. 7 is an end sectional view of the rolling mill shown in FIG. 1;

FIG. 8 is an enlarged view of a detail of FIG. 7;

FIG. 9 is a fragmentary view of a detail;

FIG. 10 is a fragmentary view showing the association of the mill screw and the upper back-up roll chock;

FIG. 11 is a section taken generally on line 11-11 of FIG. 10;

FIG. 12 is a plan view of an alternate design;

FIG. 13 is a side elevation of an alternate roll changing design in accordance with the invention;

FIG. 14 is a fragmentary plan view of a part of-the alternate design shown in FIG. 13;

FIGS. 15 and 16 are fragmentary sectional views of an alternate form of cartridge construction;

FIG. 17 is a fragmentary sectional view of another alternate form of cartridge construction; and

FIG. 18 is a fragmentary view of a means for holding the upper back-up roll assembly.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring particularly to FIGS. 1 to 9, there is shown an upper work roll 10 and a lower work roll 12 journalled in work roll chocks l4 and 16, respectively, at each roll end, and an upper back-up roll 20 and a lower back-up roll 22 joumalled in back-up chocks 24 and 26, respectively at each roll end. The chocks are all positioned in windows 28 at each end of the mill housing 30, the work roll chocks l4 and 16 being provided with liners l5 and 17, respectively, which adapt the chocks for positioning within the mill. The upper backup roll chocks 24 are loaded by the mill screw 32 and are provided with a rim portion 34 adapted to be engaged by an overhead balancing means for supporting the same during mill operation and a work roll changing operation. The lower back-up roll chocks 26 rest at the lower portion on the mill housing 30. All of the above-described construction is typical of conventional rolling mills.

In accordance with the invention, means are provided for supporting the work roll chocks, and of course the work rolls joumalled therein, during a roll changing operation in which the work rolls are removed from the mill housing to permit the insertion of a new set of work rolls. To this end there is provided a cartridge means, generally indicated at 40, composed of a first pair of chock engaging members 42 associated with the work roll chocks at the operator side of the mill housing 30 adjacent the roll changing station, and a pair of chock engaging members 44 associated with the work roll chocks at the drive side of the mill housing, whereat the drive spindles are generally located. The members 42 and 44 are structurally interconnected by ties 46 extending therebetween. The members 42 are structurally interconnected by means of a framework 48 provided with a hook member 49 adapted to be engaged by the roll pulling mechanism as will be described more fully hereafter.

Means are provided for supporting the cartridge means 40, and of course the work roll chocks carried thereby, when said cartridge means is positioned within the mill housing. Such means comprises a pair of rails 50 which extend from one end of the mill housing 30 to the other at a location beneath said chock engaging members 42 and 44. The cartridge means 40 comprises a pair of wheel means adapted to ride on each of said rails 50. As shown in FIG. 8, each wheel means comprises a wheel 52 rotatable on a horizontal axle 54 carried by a bracket 56 provided with a vertically extending pin 58 rotatably received in a suitable bearing means within the associated chock engaging member 42 or 44. By this arrangement, each of the wheels 52 is movable along the rails 50 and, for a purpose to be described hereafter, is rotatable on a vertical axis.

Means are provided for raising and lowering the rails 50 during a roll changing operation. Such means are best shown in FIG. 2 and comprise a first pair of rail lifting means 60 associated with the end of the rails 50 adjacent the roll changing station. Rail lifting means 60 includes a hydraulic cylinder means 62 which has its actuator rod connected to a crank arm arrangement 64 which includes a finger 66 pivotably movable into contact with the lower portion of said rail 50. The rail lifting means 60 is mounted on a roll changing platform 160 to be described more fully hereafter.

There is provided a second pair of rail lifting means 70 at the ends of the rails 50 adjacent the drive end of the housing. Each rail lifting means 70 includes a hydraulic cylinder means 72 which has its actuator rod connected to a crank arm arrangement 74 including a finger 76 pivotably mounted for movement to contact the lower end of the associated rail 50.

When it is desired to raise the rails 50, the cylinders 62 and 72 are actuated to cause the fingers 66 and 76 to move upwardly to contact the rails 50 and raise them to a desired height. The rails 50 normally rest on the lower back-up roll chocks 26 and their movement upwardly is limited by a pair of cooperating shoulders on the rails and the roll changing platform 160 as is best shown in FIG. 9. The upward movement of the rails 50 serves to raise them to a positionin alignment with rails on the roll changing platform 160, as will be described more fully hereafter.

The upward movement of the rails 50 also'serves to raise the cartridge 40 upwardly, this upward movement of the cartridge being utilized to separate the work roll chocks a preset amount as is required for a roll changing operation. It will be noted that the upward movement of the cartridge 50 is made possible by reason of the raising of the upper back-up roll chock 24 which is usually the first step in the conventional roll changing operation. The manner in which the raising of the cartridge 40 operates to open up the work roll chocks l4 and 16 will be described with reference to FIG. 8 where the construction of the chock engaging members 42 is shown, it being apparent that the same construction and operation occurs with respect to the other chock engaging members 44.

Referring to FIG. 8, it will be seen that the member 42 is provided with an upper shoulder 80 and a lower shoulder 82. The upper shoulder 80 is arranged in alignment with and to contact the lower end of the liner 15 of the upper work roll chock 14. The lower shoulder 82 is arranged in alignment with and to contact the lower end of the liner 17 for the work roll chock 16. It will be apparent from FIG. 8 that during an upward movement of the cartridge, the shoulder 80 first comes into contact with the liner 15 to thereby cause the upper work roll chock 14 to separate from the lower work roll chock. During the final stages of the upward movement of the cartridge, the shoulder 82 comes into contact with the liner 17 to raise the lower work roll chock 16 slightly above the lower back-up roll chock 26. Accordingly, the work roll chocks l4 and 16 are clear of contact with any part of the mill and are maintained in a separated condition by the cartridge at the end of its upward movement. The separated condition of the work rolls is illustrated in FIG. 2.

Means are provided for clamping the cartridge 40 to the mill housing 30. Such means comprises a gate 42 which locks behind the mill housing and is actuated by a cylinder 45 between locking and unlocking positions. Cartridge 40 is provided with a shoulder 39 which contacts the front of the mill housing 30 when it is locked to the mill housing by the clamping means.

Means are provided to provide a clearance between the bottom ofthe mill screw 32 and the upper back-up roll chock 24. It is important that this clearance be provided quickly in a roll changer construction. The purpose of the clearance, is, of course, to permit the overhead balancing system to raise the upper back-up rolls away from the work rolls to provide sufficient clearance for a roll changing operation.

One form of such clearance providing means is shown in FIGS. 10 and 11 and a second form is shown in FIG. 12.

Referring to FIGS. 10 and 11, a cavity 83 is formed in the upper end of the upper back-up roll chock 24. Cavity 83 is open at one end, is located beneath the mill screw 34, and is adapted to contain a cylindrical spacer 84 carried on the end of an arm 86 mounted on a vertically extending pin 88 rotatably mounted in a support 90 on the back-up roll chock 24. A crank arm 92 is also mounted on the pin 88 and has its other end connected to the extended end of the actuator rod 94 of a hydraulic cylinder 96 mounted on the chock 24. A platform 98 is mounted on chock 24 adjacent the open end of the cavity 83 as is best shown in FIG. 1 1.

For a roll changing operation, the spacer 84 is moved from the solid line position shown in FIG. 11 underneath the mill screw 32 to the dashed line position on the top of the platform 98 by the operation of the hydraulic cylinder 96 to extend its actuator rod 94. The

- actuating movement is transmitted through crank arm 92, pin 88 and arm 86 as will be apparent from a consideration of FIGS. 10 and 11. In this manner, it is possible to quickly move the spacer 84 from a position underneath the mill screw 32 to a position clear thereof when it is desired to provide clearance between the bottom end of the mill screw 32 and the upper back-up roll chock 24. As was discussed above, this clearance was necessary at the beginning of a roll changing operation when the upper back-up roll must be raised to permit separation of the work roll chocks.

The form of clearance providing means shown in FIG. 12 comprises a cavity or bore 100 formed in the upper end of the back-up roll chock 24 beneath the mill screw 32. Although not shown in FIG. 12, the mill screw 32 is directly above and in alignment with a spacer formed of two semi-cylindrical parts 102, each of which is movable from the solid line position in FIG. 12 to the dashed line position to provide for the necessary clearance underneath the mill screw. The means for actuating the spacer parts between such positions comprises a hydraulic cylinder means 106. At one end, the body of cylinder 106 is connected to a crank arm 108 while the actuator rod 110 of the cylinder means has its extended end connected to a crank arm 112. Crank arm 108 is fixedly connected to a pin 114 which is rotatably mounted in a bracket support 116 mounted on the back-up roll chock 24. Crank arm 112 is fixedly connected to a pin 118 which is rotatably mounted in support 116. Each of the spacer parts 102 has mounted therein a vertically extending pin 120 which projects downwardly for connection with a slide 122 movable within a guide slot 124 formed in the bottom of the cavity 100. A pair of link members 128 are provided to interconnect the rotatable pins 114 and 1 18 to transmit the rotating movement thereof to the spacer parts 102. To this end the link members 128 are fixedly secured to the pins 114 and 118 at one end and engage the pins 120 in a slotted portion at the other end.

It will thus be apparent that the operation of the hydraulic cylinder 106 functions to move the spacer parts 102 between the solid and dashed line positions shown in FIG. 12. In the solid line position, the cylinder 106 is shown in the extended position which will position the spacer parts 102 together as shown. When the cylinder 106 is actuated to retract the extended actuator rod 110, it will be apparent that the crank 108 will cause the pin 114 to rotate in a counterclockwise direction while the pin 118 will be rotated in a clockwise direction; As a result of this movement, the arms 128 are moved apart and cause the spacer parts 102 to separate, the slides 122 moving within the slots 124 to guide the spacer parts 102 to the dotted line position.

Means are provided for pulling a cartridge 40 containing the separated work rolls from an opened mill, which means is also operative to push a new cartridge back into the mill during a roll changing operation. Such means is best shown in FIG. 2 and comprises a roll changing cylinder means 140 supported on the underside of a movable floor plate 142. The floor plate 142 is supported on two pairs of pivotal links 144 and 146 fixedly mounted on pins 148 and 150, rotatably mounted on supporting beam members 149 and 151 respectively. The links 144 and 146 support the floor plate 142 during its movement between the raised operative position shown in FIG. 2 and a lower position in which the floor plate is aligned with the floor line of the mill. The floor plate 142 is actuated between such positions by a hydraulic cylinder means 152 which has its actuator rod connected to a crank arm 154 secured to pins 150 for rotating the same and the links 146 secured thereto. Preferably link 144 will be secured by a lock pin 145 against the push-pull action of cylinder 140.

Supported on the extended end of the actuator rod 141 of cylinder 140 is a cartridge engaging hook member 156. The end of the hook member extends downwardly and is shaped to engage the hook member 49 from the top thereof, as is best shown in FIG. 2. At its lower end, the hook member 156 carries a pair of wheels 158 which support this hook member when it moves to an extended position. This position is illustrated in FIG. 1, it being noted that the wheels 158 will ride along the roll changing platform 160 located between the floor plate 142 and the rails 50.

Means are provided for supporting a cartridge 40 at the roll changing station adjacent the mill such as when a cartridge has been pulled from the mill during a roll changing operation (as illustrated in FIG. 2) or when a new cartridge is aligned with the mill in preparation for insertion into the mill. Such means comprises the roll changing platform indicated generally at 160. The platform 160 is constructed of a plurality of beam members arranged in transverse relation and is provided with a plurality of vertically extending legs 161 for supporting the platform on the foundation while permitting removal of the entire roll changing: platform framework such as will be necessary during a. back-up roll changing operation. The roll changing platform 160 is covered by suitable floor plates, not shown in the drawings for the sake of clarity, except for the various rail portions to be described hereafter, which rail portions are mounted flush with the floor plates.

The roll changing platform is provided with a pair of main rails 162 which are aligned with the rails 50in the mill and provide, in effect, an extension thereof outside of the mill. Platform 160 also comprises a pair of cross rails 164 which extend transversely to the rails 162. The rails 164 extend to one side of what may be termed the roll changing station which is generally encompassed by the area enclosed by the rails 162 to an area which may be termed the roll loading station. In FIG. 1 there is shown a new cartridge 40', which will be inserted into the mill after the carriage 40 shown in the mill is removed, such cartridge 40' being located at the roll loading station.

At each of the four intersections of the rails 162 and 164, there is provided a rotatable rail means which is shown in detail in FIG. 6. Each rotatable rail means 170 comprises a rotatable circular plate 172 which is supported on roller bearing means 174 and is mounted on a downwardly projecting pin 176 journalled in a bushing 178, this assembly being mounted on one of the beam members forming the platform 160. Secured on top of the plate 172 is a short rail piece 180 provided with a cylindrical depression 182 adapted to receive the wheels 152 on a cartridge. It will be apparent that the rail piece 180 is adapted to extend across the gap between the rails 164 and 162 when it is positioned in alignment therewith.

Means are provided for actuating the rail pieces 180 through a ninety degree turning movement to extend along the rails 162 as is shown in FIGS. 1 and 4 or to extend along the rails 164 as is shown in FIG. 5. Such means is best shown in FIG. 4 and comprises a pair of hydraulic cylinder means mounted on the roll changing platform 160 and having the extended ends of their actuator rods connected to crank arm 192 secured to the pins 176 of two of the rotatable rail means 17 0. Conventional tie rod means are provided to interconnect the pins 176 of the last-mentioned rail means with the pins 176 of the other two rotatable rail means 170. This tie rod means comprises a tie rod 194 interconnected with crank arm 196 and 198 secured to the pins of the associated rotatable rail means 170.

Referring to FIG. 4, the rotatable rail means 170 are shown in the position in alignment with the rails 162. It will be apparent that in this position the rail pieces 180 span the gaps in the rails 162 to permit a wheel to move along the rails as desired. When it is desired to span the gaps in the rails 164. The cylinders 190 are actuated to extend their actuator rods to thereby cause the crank arms 192 to turn 90 in the direction shown by the arrows in FIG. 4.

It will be noted that the above-described rotation of the rail pieces 180 is performed normally during a roll changing operation when a cartridge has been moved to a position in which its wheels 52 are engaged with the rail pieces 180. This engagement is improved by reason of the cylindrical depressions 182. Thus, when the rail pieces are turned 90, they will cause a corresponding rotation of the rotatably mounted wheels 52, this being utilized to enable a change in direction in which the cartridge can be moved.

Means are provided for causing a side shifting movement of a cartridge means 40 on the roll changing platform 160. Such means comprises a side shifting hydraulic cylinder means 200 pivotally mounted on the underside of platform 160 by a suitable support means 202. At its extended end, the actuator rod 204 of the side shifting cylinder means 200 is pivotally secured to a bracket 206 which is connected to a cross beam member 208. Member 208 is interconnected along with a plurality of frame members 210 to 214 to a pair of side frame members 128 to form a side shifting framework generally indicated at 220. The frame members 218 each have supported thereon a pair of wheels 222 and 224 adapted to ride in guide channels or rails supported on the bottom of the roll changing platform 160. These guide channels include a pair of horizontal guides 225 and a pair of downwardly extending guides 226. When the actuator rod 204 is fully extended, the wheels 222 will be positioned within the guides 226 whereby the fingers 230 will be positioned below the floor line. This position is shown in dashed lines at the left end of FIG. 5. In this position, the wheels 224 are within the guides 225. However, as the actuator rod is retracted, the wheels 222 ride up guide 226 into the guide 225 and from this point on both pair of wheels 222 and 224 will ride in the horizontal guides 225 as the actuator rod is retracted.

Mounted on each of the frame members 218 is a pair of upwardly extending fingers 230. As shown in FIG. 5, the upper ends of the fingers 230 are adapted to engage the chock engaging portions 42 and 44 of a cartridge means mounted on the rails 164 at the loading station of the apparatus. The engaging position is shown in solid lines in FIG. 5. By extending the rod 204 beyond the position shown in FIG. 5, it is possible to position the fingers 230 below the floor line of the mill in a nonoperative position as shown in dashed lines in FIG. 5. However, during operation, the actuator rod 204 will be retracted into the cylinder 200. When this occurs, the fingers 230 will project upwardly through slots 232 formed in the floor plate 234 above the roll changing platform 160 and move into engagement with the car tridge to thereby move the cartridge along the rails 164 in the direction toward the roll changing station. The fingers 230 are moved toward the solid line position in FIG. 5 toward the right to the dashed line position shown at A to move a cartridge from the loading station to the roll changing station.

There is provided a pair of rails 240 (see FIGS. 1 and 3) in alignment with the rails 164 and providing, in effect, an extension thereof in the location adjacent the roll changing station. Typically, the rails 240 would extend across a scale pit of the mill which is covered by a suitable floor plate or would extend to the floor directly depending on the mill layout. The rails 240 form no part of the roll changing platform but are simply a continuation of the rails 164 and are constructed and arranged to support a work roll supporting carriage 40 as it is discharged from the roll changing station during a roll changing operation as will be described more fully hereafter.

There is provided means for pulling the back-up rolls from the mill when it is desired to change these rolls. Such means comprises a back-up roll changing cylinder 242 supported beneath the roll changing floor plate 142 and having its actuator rod 244 connected to a coupler 246 which is connected to the lower back-up roll chock 26 as is best shown in FIG. 2. It will be apparent that by operation of the cylinder 242 to retract rod 244, the back-up roll chock 26 may be pulled from the mill. Of course, prior to this, it will be necessary to remove the roll changing platform 160 to provide an open area into which the back-up roll chock 26 and the back-up roll supported thereby can be moved.

In describing the operation of the roll changer in accordance with the invention, let it be assumed that it is desired to change the work rolls in the mill and replace it by a new set of work rolls which are positioned on the cartridge means 40. This arrangement is shown in FIG. 1 wherein the cartridge 40 is in the mill and the cartridge 40' has been assembled with the new work rolls and set at the loading station in preparation for a roll change. Also, the floor plate 142 has been moved to the raised position and the roll changing cylinder 140 has been actuated to extend its actuator 141 to the position shown in FIG. 1. The hook means 156 is thus positioned above the hook member 49 as is shown in the solid line position of FIG. 9 whereby hook means 156 is adapted to receive the hook means 49 when the latter is raised.

The rolling mill is then stopped and the clearance providing means such as the one shown in FIGS. 10 and 11 is actuated to provide a clearance beneath the mill screw 32 as was described above. The back-up roll chock 24 is then raised upwardly to provide clearance above the work rolls by means of the usual overhead balancing means (not shown).

The rail lifting means 60 and are then actuated to raise the rail means 50 upwardly by means of the fingers 66 and 76 to a position in which the rails 50 are aligned with the rails 162 on the rail changing platform 160. As was discussed above, the raising of the rails also results in the rail engaging chocks 42 and 44 causing the predetermined separation of the work rolls from each other and from the lower back-up roll. The raising of the rails 50 also raises the hook means 49 of the cartridge 40 to the dashed line position as shown in FIG. 9 in which the hook member 49 engages the hook 9 member 156 of the roll changing means. The clamping means holding the cartridge to the mill housing are then opened. I

The parts are now in the position illustrated in FIG. 1. The roll changing cylinder 140 is then actuated to retract rod 141 and pull the cartridge 40 and the work rolls supported thereon from the mill onto the roll changing platform 160. Prior to this, the rail pieces 180 of the rotatable rail means 170 have been actuated to the position in alignment with rails 162 as is shown in FIG. 1. As the cartridge 40 is pulled onto the rail changing platform 160, the wheels 52 thereof pass from rails 50 onto rails 162. This movement is terminated when the four wheels 52 come to rest onto the four rail pieces 182, this position being illustrated in FIG. 2. The rotatable rail means 170 are then actuated to turn the rail pieces into alignment with the rails 164, this movement turning the wheels 52 of cartridge 40 to the position best illustrated in FIG. 5. The cartridge 40 and 40 are now positioned side-by-side as shown in FIG. and are in condition for a side shifting movement. This is achieved by the side shifting cylinder 200 which had been positioned with its actuator rod 204 fully extended whereby the finger 230 was in the lower position. The cylinder 200 then retracts the rod 204 which results in movement of the finger 230 into contact with the cartridge 40' as shown in the solid line position of FIG. 5. The fingers 230 are continuously moved across the loading station being guided by the wheels 222 and 224 which ride in the horizontal guide channels 225. This movement of fingers 230 moves the cartridge 40 along the rails 164 and causes cartridge 40 to contact the cartridge 40 at the pusher fingers 57 on the wheel brackets 56 of the two wheels 52 adjacent the platform 160. Thus, both the cartridges 40 and 40 are moved along the rails 164 until the cartridge 40' is positioned with its wheels in engagement with the rail pieces 182 of the rotatable rail means 170, the cartridge 40' now being at the roll changing station. At the same time, the cartridge 40 has been moved from the roll changing station onto the rails 240 adjacent thereto. The cartridge 40 may now be removed to a location where a new set of work rolls can be positioned thereon. It will be noted that during this side shifting movement, the hook member 49 of cartridge 40 simply moves out of engagement with the hook member 156 since there is nothing blocking such movement and the hook member of the cartridge 40 will simply be moved into engagement with the hook member 156.

The cartridge 40 is now in position for being pushed into the mill. First, the rotatable rail means 170 are actuated to position the rail pieces 182 in alignment with the rails 162. This is achieved by a 90 rotation which also serves to rotate the wheels 52 of cartridge 40 in alignment with the rails 162. The rail changing cylinder 140 is now actuated to extend the actuator rod 141 and push the cartridge 40' into the mill. During this pushing movement, the wheels 52 on the cartridge 40' ride along the rails 162 and onto the rails 50. Rail lifting means 60 and 70 are then actuated to lower the rails 50 and place the work rolls in the mill in preparation for a rolling procedure. The cartridge is then locked to the mill housing by the clamping means 43 and 45. The mill screw clearance providing means shown in FIGS. 10 and 11 is actuated to replace the spacer beneath the mill screw after the upper back-up roll has been lowered on top of the new work rolls and the mill is closed in preparation for a rolling operation.

An alternate form of a work roll changer in ac cordance with the invention is shown in FIGS. 13 and 14. This form is particularly adapted for incorporation into existing mills where it is desirable to have the roll changing means arranged as compactly as possible, such as within the area of the roll changing station. The components of the form shown in FIGS. 13 and 14 are constructed essentially the same as those described above in FIGS. 1 to 9 wherefore, the same reference numerals with primes added will be used for corresponding parts and only the differences in construction will be described.

There is provided a work roll supporting cartridge 250 similar to the cartridge 40 except that the member 252 which is engaged by the roll changing means, provides a downwardly facing slot adapted to receive the engaging member as will be described hereafter. The cartridge means has wheels 52' which are supported on rails 50 which are raised and lowered by rail lifting means including the rail lifter 60 shown in FIG. 12.

There is provided a roll changing platform 160' having main rails 162' aligned with the rails 50' and cross rails 164 extending transversely to rails 162. Mounted on the platform 160' are rotatable rail members 170 which are turned to align their rail pieces 182' with either rails 162' or rails 164' in the manner described above with respect to the first embodiment. The rotatable rail means 170 are actuated by the cylinders 190' and are interconnected by tie rods 194' and crank arms 196' and 198'. The platform is provided with a slot 256 extending the length thereof across the roll changing station midway between main rails 162' and parallel thereto. This slot 256 is adapted to accommodate the passage of the cartridge engaging fingers of the roll changing means as will be described more fully hereafter.

In order to accommodate such roll changing means movement through the slot 256, the rails 164' include means for providing a gap therein. To this end, rails 164' have a split rail portion 260 which is movable across the slot 256 to close the gap shown in FIG. 14. The split rail 260 is placed in the gap providing position shown in FIG. 14 when the rotatable rail means are positioned in alignment with rails 164' and are moved to the gap closing position when the rotatable rail means is turned to be aligned with rails 164'. This is achieved by a link connecting means 262 which interconnects the split rail 260 and the crank arm 198' as is shown in FIG. 14. The link connection thus serves to interlock the split rail 260 and the rotatable rail members 170 to insure the conditions of operation described above.

With the exception of the change in the rail construction involving the split rail, the side shifting means is essentially the same as that of the first embodiment described. The side shifting means is operated by means of a side shifting cylinder shown at 200'.

Means are provided for pulling a cartridge from and pushing a new cartridge into the: mill during a roll changing operation. Such means is located at the roll changing station beneath the platform 160' and comprises a push-pull, link-type chain means 270. Chain means 270 are arranged to be guided for movement within a pair of horizontal guide channels 272 and 274 and around a spindle 276. The chain means 270 is of the type which will transmit forces in either direction along its length when it is confined. The confinement of the chain means 270 is provided by the guide channels 272 and 274. As is shown in FIG. 13, the trailing edge of the chain means 270 extends within a pair of spaced guide channels 272 while the leading end of the chain means 270 is provided with a member 278 which is guided within a pair of upper guide channels 274. Member 278 also supports the cartridge engaging latch member 280. As shown in FIG. 13, the leading end member 278 is movable between the solid line position to the dashed line position while in engagement with the cartridge 250. The drive for the chain means 270 includes a reversible electric motor 282 which drives the spindle shaft 277 by way of a clutch 284 and a speed reducing means 286.

At the end thereof adjacent the mill, the upper guide channels 274 are provided with portions 286 which are pivoted at 288 for articulation between the two alternate positions shown in FIG. 13. The movement of portions 286 between its positions is achieved by means of a hydraulic cylinder means 290 pivotally mounted at its bottom on the support legs 292 for the platform 160' and having the end of its actuator rod secured to portion 286 at a medial portion thereof. It will be apparent that by actuating the portions 286 between the positions shown in FIG. 12, it is possible to connect and disconnect the latch member 280 into engagement with the slot in coupling portion 252.

The operation of the form of the invention shown in FIGS. 13 and 14 is essentially the same as the first described embodiment the main exceptions being that the motor driven chain means is utilized to move a cartridge into and out of the mill from the roll changing station on platform 160 and that the rails 164' open and close the gap as described above.

In FIGS. 15 and 16, there is shown an alternate form of cartridge construction. In some cases it may be desirable to provide a tie between the chock engaging members 44 of a cartridge such as cartridge 40 to provide additional strength, such as in the case of very wide mills. The best place available for locating this tie is just beneath the drive spindle of the mill which drives the lower work roll. A suitable tie arrangement is shown in FIG. 15, the lower work roll drive spindle being shown at 290 and the tie member at 292. This tie member 292 will extend across the mill between the chock engaging members 44 of the cartridge 40. It will be noted that when the tie member 292 is installed, there will be very little clearance between this cartridge attached member and the drive spindle 290 of the mill. Accordingly, it is not possible to raise the cartridge 40 by the rail lifting means since the tie member 292 will contact the drive spindle 290. Accordingly, the chock engaging members of the cartridge are constructed in the manner illustrated in FIG. 16 which permits the raising of the cartridge wheels only by the rail lifting means instead of a raising of the entire cartridge.

To this end, the upper portion of the chock engaging members of the cartridge are provided with a transversely extending slot 302 adapted to receive a finger member 304 which projects inwardly so that its inner end 305 is located beneath and in alignment with the liner 15 of the upper work roll chock 14. A sleeve member 306 is fixedly secured within a bore 308 in finger member 304. The sleeve 306 is movably received within a bushing 310 positioned within a bore in the lower portion of the chock engaging member. The cartridge wheel means is essentially the same as that disclosed in FIG. 7 wherefore corresponding parts have been given corresponding numbers with double primes added, but is different in that the pin 58" extending upwardly from the wheel supporting bracket 56' is much longer and extends upwardly through the sleeve 306 for engagement at its upper end with a nut 311 which connects the pin 58" to the finger member 304 to provide for conjoint movement of the wheel means and the finger member 304. The pin 58" is rotatably received within a bushing 312 positioned within the sleeve member 306 and a bushing 314 located at the lower portion of the chock engaging member 42. As shown in FIG. 15, there is a spacing between the top of the wheel bracket 56 and the lower wall 320 of the chock engaging member. There is also a spacing between the liner 15 of the upper work roll chock l4 and the upper wall of finger member end 305. The chock engaging member is also provided with a shoulder 82" which is located beneath and in alignment with the liner 17 of the lower work roll chock 16.

Thus, the arrangement shown in FIG. 15 permits the raising of the wheel means by the rails 50 without producing a raising of the cartridge itself throughout a considerable distance. It will be apparent that as the rails 50 are moved upwardly, the wheel means moves up freely without any restriction. During this movement, the wheel means raises the finger 304 upwardly without resistance until its end 305 contacts the liner 15 of the upper work roll chock 14. Continued movement of the wheel means will serve to raise the upper work chock 14 above the lower work roll chock 16. When the wheel means comes into contact with the bottom wall 320 of the cartridge, it will cause movement thereof. However, this will only occur at the end of the rail raising movement and will be for only a short distance. This short distance may be utilized to raise the lower work roll chock 16 slightly above the lower back-up roll chock 26 by the action of the shoulder means 82" in contacting the liner 17 of the lower work roll chock 16 to move the same upwardly a small distance. The upward movement of the rails 50 places them in alignment with the rails of the roll changing platform and the cartridge may be pulled from the mill. Another alternate form of cartridge means in accordance with the invention is shown in FIG. 17. This form is particularly adapted for incorporation into an existing mill which does not have an overhead balance for the upper back-up roll but instead has provided the upper back-up roll balancing in the vertical legs of the upper back-up roll chock. Since the utilization of a cartridge design in accordance with the invention may require the removal of the balancing means from the existing back-up roll chock, it is necessary to provide for such balancing means in the redesigned mill. To this end, the chock engaging members of the cartridge are provided with a suitable number of balancing cylinders such as the cylinder 350 shown in FIG. 17. It is noted that this cylinder is provided in a bore 352 in the chock engaging members and is adapted to move upwardly into contact with the lower end of the upper back-up roll chock 24 to provide a support therefor as desired.

In FIG. 18, there is shown means for use in a rapid work roll changer for holding the upper back-up roll assembly during a work roll change. This means is useful where there is insufficient room to provide an overhead work roll support at the top of the upper back-up roll chock. Such means comprises a lug member 360 mounted on the upper back-up roll. A support means including a hydraulic cylinder 364 and a lug engaging block 366 (which is secured to the end of the actuator rod of cylinder 64 and is guided in a bore in cylinder 368) is mounted on the mill housing adjacent the lug 360 as shown in this Figure. The lug member 360 and the block 366 are provided with inclined, stepped surfaces 362 and 367, respectively, which are arranged to permit secure mating contact. There will be a similar arrangement on the opposite side of the back-up roll chock. It will thus be apparent that by actuating the cylinder 364 to extend its actuator rod, the block member 366 will move into engagement with the lug 360 to thereby support the upper back-up roll chock from the sides of the mill housing.

Briefly, some of the advantages of the invention are that (l) the cartridge design allows for simple mounting, dismounting and transportation of the rolls with only two cartridges being required for each stand; (2) the cartridge can be used as a stool for back-up roll changing; (3) the side shifting means does not require a side shifting car since the cartridge itself has turnable wheels permitting it to be side shifted; (4) there is no opening in the floor and no trailing floor plates required in the side shifter construction; and (5) the side shifter is easily removable for back-up roll changmg.

It is to be understood that various changes may be made in the construction and arrangement of parts without departing from the scope of the invention.

l claim:

1. In a rolling mill having upper and lower work rolls defining a pass line, a mill housing having windows at each end, and upper and lower roll chocks having the ends of the said upper and lower work rolls, respectively journalled therein and adapted to be removably mounted in said housing windows; a cartridge means for supporting said work roll chocks during movement into and out of the mill housing including a pair of side leg means extending between said housing windows and having chock engaging members at each housing window, rail means extending horizontally between said housing windows for supporting said cartridge means within the mill housing, said cartridge means having wheel means mounted thereon and arranged to be supported on said rail means, said chock engaging members having portions movable into supporting engagement with each of said work roll chocks for supporting the same during movement of the cartridge into and out of the mill housing.

2. A rolling mill according to claim 1 in which said cartridge means includes a tie means interconnecting said leg means at one end thereof.

3. A rolling mill according to claim 1 wherein said cartridge wheel means are rotatably mounted on the cartridge for a turning movement about a 'vertical axis 14 from a position aligned with the direction of movement of the cartridge into and out of the mill to a position transverse thereto.

4. A rolling mill according to claim 1 including a roll changing platform adjacent one of said housing windows and having first rail means arranged to be aligned with said mill housing rail means for receiving said cartridge wheels therefrom, and means for moving said cartridge means between a position in the mill housing on said mill housing rail means and a position on said roll changing platform on said first rail means thereof.

5. A rolling mill according to claim 4 including means for lowering and raising said mill housing rail means between a lower position and a raised position, said cartridge means being constructed and arranged to position said upper work roll on said lower work roll in said lower position of said rail means, said chock engaging members having portions engaging said upper work roll chocks during the raising of said mill housing rail means from said lower position to said raised position to raise said upper work roll chocks above said lower work roll chocks into a predetermined separated condition, said mill housing rail means being aligned with said first rail means of said roll changing platform in said raised position thereof.

6. A rolling mill according to claim 5 wherein said cartridge wheel means are rotatably mounted on the cartridge for a rotating movement from a position aligned with the direction of movement of the cartridge into and out of the mill to a position transverse to such cartridge movement.

7. A rolling mill according to claim 6 wherein said roll changing platform includes a second rail means extending transversely to said first rail means and intersecting the same, said cartridge wheel means being constructed and arranged to be positioned at the intersections of said first and second rail means, means at the intersections of said first and second rail means for guiding said cartridge wheel means for movement along either said first and second rail means.

8. A rolling mill according to claim 7 wherein said wheel guide means includes a rail portion for supporting said cartridge wheel means at said intersections and means for rotating said rail portions to extend in alignment with either said first or said second rail means, said rail portions being constructed and arranged to engage said cartridge wheel means during said turning movement for rotating the same into alignment with either said first or second rail means.

9. A rolling mill according to claim 7 wherein said roll changing platform defines a roll changing station from which a cartridge means may be moved into and out of the mill housing, means defining a loading station alongside of said roll changing station including rail means aligned with said second rail means of said roll changing platform for guiding the cartridge wheel means therealong from said loading station to said roll changing station by way of said second rail means and said loading station rail means.

10. A rolling mill according to claim 9 including means for pushing a cartridge means from said loading station onto said roll changing station.

11. A rolling mill according to claim 10 including a second cartridge means for supporting a second set of work roll chocks and including a pair of side leg means having chock engaging members and rotatable wheel means adapted to ride on said mill housing rail means, on said first and second roll changing rail means and on said loading station rail means, means on said second cartridge means adapted to contact a cartridge means positioned at said roll changing station with said second cartridge means positioned at said loading station and for pushing a cartridge sideways from said roll changing station when said second cartridge is moved from said loading station to said roll changing station by said pushing means.

12. In a rolling mill according to claim 1 having an upper back-up roll positioned above said upper work roll in said mill housing, a lower back-up roll positioned below said lower work roll in said mill housing, and upper and lower back-up roll chocks having the ends of said upper and lower work rolls, respectively, journalled therein; wherein said chock engaging members are constructed and arranged to be positioned between said upper and lower back-up roll chocks for supporting said upper back-up roll chocks on said lower backup roll chocks with said chock-engaging means positioned therebetween.

13. In a rolling mill according to claim 5 wherein said means for moving said cartridge means from the mill housing to said roll changing platform comprises a hook means having a downwardly facing coupling opening, said cartridge means including means for coupling the same to said cartridge moving means, said coupling means including a member mounted on said cartridge means movable into coupling engagement with said hook means during the raising movement of said cartridge means.

14. A rolling mill according to claim 13 wherein said cartridge moving means includes a power operated cylinder having an actuator rod movable from an extended position whereat it is engageable with said coupling means of said cartridge means in the mill housing to a retracted position across the top of said roll changing platform whereby a cartridge means connected to said actuator rod during said movement will be pulled from the mill housing onto the roll changing platform.

15. In a rolling mill according to claim 4 wherein said cartridge moving means includes a push-pull chain means having a forward end movable from a position at one end of said roll changing platform whereat it is engageable with a cartridge means in the mill housing to a position at the other end of said roll changing platform, said movement of said chain means being across the roll changing platform parallel to said first rail means thereof whereby a cartridge means connected to the forward end of said chain means will be pulled from the mill housing onto the roll changing platform.

16. In a rolling mill according to claim 15 including means for guiding the forward end of said chain means and confining said chain means in a path parallel to said first rail means and means for driving said chain means through such movement thereof including a power driven sprocket means engaging said chain means.

17. In a rolling mill according to claim 15, means defining a slot extending across said roll changing platform and adapted to receive said forward end of said chain means during said movement across said platform, said slot intersecting said second rail means, rail portions located at said intersections of said slot and said second rail means for closing said slot to permit the passage of the cartridge wheels thereacross.

18. In a rolling mill according to claim 17 including means interlocking said slot closing rail means and said means for turning said rail portions for conjoint movement thereof.

19. In a rolling mill according to claim 12 having mill screws arranged to contact the upper portion of the upper back-up roll chocks; means for providing a clearance between a mill screw and an upper back-up roll chock including a cavity formed in the upper portion of the upper back-up roll chock beneath the mill screw, a spacer member mounted in said cavity and means for moving said spacer member from a position in said cavity beneath said mill screw to a position clear of said mill screw to permit upward movement of the upper back-up roll chocks relative to the mill screw with said mill screw moving into said cavities.

20. In a rolling mill according to claim 19 wherein each said cavity has an opening at one portion thereof, said spacer means being movable through said opening during movement thereof between said positions thereof.

21. In a rolling mill according to claim 19 wherein said cavity is enclosed at its sides and substantially larger than said mill screw at two end portions thereof, said spacer means being constructed of two members movable by said spacer moving means from a position beneath the mill screw to a position within said enlarged end portions of said cavity clear of said mill screw.

22. A rolling mill according to claim 2 wherein said cartridge means includes a second tie means interconnecting said leg means at the other end thereof from said one end, said portions of said chock engaging members which are movable into supporting engagement with said upper work roll chocks including members associated with said wheel means for movement upwardly relative to said cartridge means during a raising movement of said wheel means whereby said upper work roll chocks may be raised without raising the cartridge means.

23. A rolling mill according to claim 12 including power-operated means mounted in each of said chock engaging members of said cartridge means for movement upwardly into contact with the lower end portions of said upper back-up roll chocks for supporting the same.

24. A rolling mill according to claim 12 including means for holding the upper back-up roll chocks in said mill housing during a work roll change, said last-mentioned means including a pair of power-operated cylinder means mounted on the mill housing at each window thereof and having an actuator rod which has at its extended end a lug-engaging block, a lug member mounted on said upper back-up roll chocks adjacent said cylinder means and arranged to be engaged by said lug members when said actuator rod is extended whereby said upper back-up roll chock is supported on the mill housing by said cylinder means.

25. In a rolling mill having upper and lower work rolls defining a pass line, a mill housing having windows at each end, and upper and lower roll chocks having the ends of the said work rolls journalled therein and adapted to be removably mounted in said housing windows; means for supporting said work roll chocks during movement into and out of the mill housing, rail means extending horizontally between said housing windows for supporting said chock supporting means within the mill housing, said chock supporting means having wheel means mounted thereon and arranged to be supported on said rail means, said wheel means being rotatably mounted for rolling movement in the direction of movement of said chock supporting means into and out of the mill and in the direction transverse thereto, a roll changing platform adjacent one of said housing windows and having first rail means aligned with said mill housing rail means for receiving said wheel means therefrom, means for moving said chock supporting means from a position in the mill housing on said mill housing rail means to a position on said roll changing platform on said first rail means thereof, said roll changing platform including a second rail means extending transversely to said first rail means and intersecting the same, said wheel means being constructed and arranged to be positioned at the intersections of said first and second rail means, and means at said intersections for guiding said wheel means for movement along either said first and second rail means.

26. A rolling mill according to claim 25 wherein said rail means.

27. A rolling mill according to claim 25 wherein said roll changing platform defines a roll changing station from which a chock supporting means may be moved into and out of the mill housing, means defining a loading station alongside of said roll changing station including rail means aligned with said second rail means of said roll changing platform for guiding said wheel means therealong from said loading station to said roll changing station by way of said second rail means and said loading station rail means.

28. A rolling mill according to claim 27 including means for pushing a cartridge means from said loading station onto said roll changing station.

29. A rolling mill according to claim 28 including a second chock supporting means for supporting a second set of work roll chocks and including rotatable wheel means adapted to ride on said mill housing rail means on said first and second rail means and on said loading station rail means, means on said second chock supporting means adapted to contact a chock supporting means positioned at said roll changing station with said second chock supporting means positioned at said loading station and for pushing a chock supporting means sideways from said roll changing station when said second chock supporting means is moved from said loading station to said roll changing station by said pushing means.

30. A rolling mill according to claim 1 in which said chock supporting portions of said chock engaging member are constructed and arranged to support said chocks in a predetermined separated condition. 

1. In a rolling mill having upper and lower work rolls defining a pass line, a mill housing having windows at each end, and upper and lower roll chocks having the ends of the said upper and lower work rolls, respectively journalled therein and adapted to be removably mounted in said housing windows; a cartridge means for supporting said work roll chocks during movement into and out of the mill housing including a pair of side leg means extending between said housing windows and having chock engaging members at each housing window, rail means extending horizontally between said housing windows for supporting said cartridge means within the mill housing, said cartridge means having wheel means mounted thereon and arranged to be supported on said rail means, said chock engaging members having portions movable into supporting engagement with each of said work roll chocks for supporting the same during movement of the cartridge into and out of the mill housing.
 2. A rolling mill according to claim 1 in which said cartridge means includes a tie means interconnecting said leg means at one end thereof.
 3. A rolling mill according to claim 1 wherein said cartridge wheel means are rotatably mounted on the cartridge for a turning movement about a vertical axis from a position aligned with the direction of movement of the cartridge into and out of the mill to a position transverse thereto.
 4. A rolling mill according to claim 1 including a roll changing platform adjacent one of said housing windows and having first rail means arranged to be aligned with said mill housing rail means for receiving said cartridge wheels therefrom, and means for moving said cartridge means between a position in the mill housing on said mill housing rail means and a position on said roll changing platform on said first rail means thereof.
 5. A rolling mill according to claim 4 including means for lowering and raising said mill housing rail means between a lower position and a raised position, said cartridge means being constructed and arranged to position said upper work roll on said lower work roll in said lower position of said rail means, said chock engaging members having portions engaging said upper work roll chocks during the raising of said mill housing rail means from said lower position to said raised position to raise said upper work roll chocks above said lower work roll chocks into a predetermined separated condition, said mill housing rail means being aligned with said first rail means of said roll changing platform in said raised position thereof.
 6. A rolling mill according to claim 5 wherein said cartridge wheel means are rotatably mounted on the cartridge for a rotating movement from a position aligned with the direction of movement of the cartridge into and out of the mill to a position transverse to such cartridge movement.
 7. A rolling mill according to claim 6 wherein said roll changing platform includes a second rail means extending transversely to said first rail means and intersecting the same, said cartridge wheel means being constructed and arranged to be positioned at the intersections of said first and second rail means, means at the intersections of said first and second rail means for guiding said cartridge wheel means for movement along either said first and second rail means.
 8. A rolling mill according to claim 7 wherein said wheel guide means includes a rail portion for supporting said cartridge wheel means at said intersections and means for rotating said rail portions to extend in alignment with either said first or said second rail means, said rail portions being constructed and arranged to engage said cartridge wheel means during said turning movement for rotating the same into alignment with either said first or second rail means.
 9. A rolling mill according to claim 7 wherein said roll changing platform defines a roll changing station from which a cartridge means may be moved into and out of the mill housing, means defining a loading station alongside of said roll changing station including rail meaNs aligned with said second rail means of said roll changing platform for guiding the cartridge wheel means therealong from said loading station to said roll changing station by way of said second rail means and said loading station rail means.
 10. A rolling mill according to claim 9 including means for pushing a cartridge means from said loading station onto said roll changing station.
 11. A rolling mill according to claim 10 including a second cartridge means for supporting a second set of work roll chocks and including a pair of side leg means having chock engaging members and rotatable wheel means adapted to ride on said mill housing rail means, on said first and second roll changing rail means and on said loading station rail means, means on said second cartridge means adapted to contact a cartridge means positioned at said roll changing station with said second cartridge means positioned at said loading station and for pushing a cartridge sideways from said roll changing station when said second cartridge is moved from said loading station to said roll changing station by said pushing means.
 12. In a rolling mill according to claim 1 having an upper back-up roll positioned above said upper work roll in said mill housing, a lower back-up roll positioned below said lower work roll in said mill housing, and upper and lower back-up roll chocks having the ends of said upper and lower work rolls, respectively, journalled therein; wherein said chock engaging members are constructed and arranged to be positioned between said upper and lower back-up roll chocks for supporting said upper back-up roll chocks on said lower back-up roll chocks with said chock-engaging means positioned therebetween.
 13. In a rolling mill according to claim 5 wherein said means for moving said cartridge means from the mill housing to said roll changing platform comprises a hook means having a downwardly facing coupling opening, said cartridge means including means for coupling the same to said cartridge moving means, said coupling means including a member mounted on said cartridge means movable into coupling engagement with said hook means during the raising movement of said cartridge means.
 14. A rolling mill according to claim 13 wherein said cartridge moving means includes a power operated cylinder having an actuator rod movable from an extended position whereat it is engageable with said coupling means of said cartridge means in the mill housing to a retracted position across the top of said roll changing platform whereby a cartridge means connected to said actuator rod during said movement will be pulled from the mill housing onto the roll changing platform.
 15. In a rolling mill according to claim 4 wherein said cartridge moving means includes a push-pull chain means having a forward end movable from a position at one end of said roll changing platform whereat it is engageable with a cartridge means in the mill housing to a position at the other end of said roll changing platform, said movement of said chain means being across the roll changing platform parallel to said first rail means thereof whereby a cartridge means connected to the forward end of said chain means will be pulled from the mill housing onto the roll changing platform.
 16. In a rolling mill according to claim 15 including means for guiding the forward end of said chain means and confining said chain means in a path parallel to said first rail means and means for driving said chain means through such movement thereof including a power driven sprocket means engaging said chain means.
 17. In a rolling mill according to claim 15, means defining a slot extending across said roll changing platform and adapted to receive said forward end of said chain means during said movement across said platform, said slot intersecting said second rail means, rail portions located at said intersections of said slot and said second rail means for closing said slot to permit the passage of the cartridge wheels thereacross.
 18. In a rolling mill according to claim 17 including means interlocking said slot closing rail means and said means for turning said rail portions for conjoint movement thereof.
 19. In a rolling mill according to claim 12 having mill screws arranged to contact the upper portion of the upper back-up roll chocks; means for providing a clearance between a mill screw and an upper back-up roll chock including a cavity formed in the upper portion of the upper back-up roll chock beneath the mill screw, a spacer member mounted in said cavity and means for moving said spacer member from a position in said cavity beneath said mill screw to a position clear of said mill screw to permit upward movement of the upper back-up roll chocks relative to the mill screw with said mill screw moving into said cavities.
 20. In a rolling mill according to claim 19 wherein each said cavity has an opening at one portion thereof, said spacer means being movable through said opening during movement thereof between said positions thereof.
 21. In a rolling mill according to claim 19 wherein said cavity is enclosed at its sides and substantially larger than said mill screw at two end portions thereof, said spacer means being constructed of two members movable by said spacer moving means from a position beneath the mill screw to a position within said enlarged end portions of said cavity clear of said mill screw.
 22. A rolling mill according to claim 2 wherein said cartridge means includes a second tie means interconnecting said leg means at the other end thereof from said one end, said portions of said chock engaging members which are movable into supporting engagement with said upper work roll chocks including members associated with said wheel means for movement upwardly relative to said cartridge means during a raising movement of said wheel means whereby said upper work roll chocks may be raised without raising the cartridge means.
 23. A rolling mill according to claim 12 including power-operated means mounted in each of said chock engaging members of said cartridge means for movement upwardly into contact with the lower end portions of said upper back-up roll chocks for supporting the same.
 24. A rolling mill according to claim 12 including means for holding the upper back-up roll chocks in said mill housing during a work roll change, said last-mentioned means including a pair of power-operated cylinder means mounted on the mill housing at each window thereof and having an actuator rod which has at its extended end a lug-engaging block, a lug member mounted on said upper back-up roll chocks adjacent said cylinder means and arranged to be engaged by said lug members when said actuator rod is extended whereby said upper back-up roll chock is supported on the mill housing by said cylinder means.
 25. In a rolling mill having upper and lower work rolls defining a pass line, a mill housing having windows at each end, and upper and lower roll chocks having the ends of the said work rolls journalled therein and adapted to be removably mounted in said housing windows; means for supporting said work roll chocks during movement into and out of the mill housing, rail means extending horizontally between said housing windows for supporting said chock supporting means within the mill housing, said chock supporting means having wheel means mounted thereon and arranged to be supported on said rail means, said wheel means being rotatably mounted for rolling movement in the direction of movement of said chock supporting means into and out of the mill and in the direction transverse thereto, a roll changing platform adjacent one of said housing windows and having first rail means aligned with said mill housing rail means for receiving said wheel means therefrom, means for moving said chock supporting means from a position in the mill housing on said mill housing rail means to a position on said roll changing platform on said first rail means thereof, said roll changing platform including a second Rail means extending transversely to said first rail means and intersecting the same, said wheel means being constructed and arranged to be positioned at the intersections of said first and second rail means, and means at said intersections for guiding said wheel means for movement along either said first and second rail means.
 26. A rolling mill according to claim 25 wherein said wheel guide means includes a rail portion for supporting said wheel means at said intersections and means for rotating said rail portions to extend in alignment with either said first or said second rail means, said rail portions being constructed and arranged to engage said wheel means during said turning movement for rotating the same into alignment with either said first or second rail means.
 27. A rolling mill according to claim 25 wherein said roll changing platform defines a roll changing station from which a chock supporting means may be moved into and out of the mill housing, means defining a loading station alongside of said roll changing station including rail means aligned with said second rail means of said roll changing platform for guiding said wheel means therealong from said loading station to said roll changing station by way of said second rail means and said loading station rail means.
 28. A rolling mill according to claim 27 including means for pushing a cartridge means from said loading station onto said roll changing station.
 29. A rolling mill according to claim 28 including a second chock supporting means for supporting a second set of work roll chocks and including rotatable wheel means adapted to ride on said mill housing rail means on said first and second rail means and on said loading station rail means, means on said second chock supporting means adapted to contact a chock supporting means positioned at said roll changing station with said second chock supporting means positioned at said loading station and for pushing a chock supporting means sideways from said roll changing station when said second chock supporting means is moved from said loading station to said roll changing station by said pushing means.
 30. A rolling mill according to claim 1 in which said chock supporting portions of said chock engaging member are constructed and arranged to support said chocks in a predetermined separated condition. 